In a known method for determining the carbon content of steel material or making judgment of whether the steel material is a steel material consisting of a high-strength steel containing an addition agent for improving the steel strength or is a steel material consisting of an ordinary steel in which the addition agent is not contained, an inspector visually observes a spark produced when the steel material is ground by a grinder or the like, and the inspector makes determination or judgment from the state of spark observed. Some addition agents for improving the steel strength improve the steel strength by enhancing hardenability, solid solution effect, or the like. As a specific example of such an addition agent, V, Cr, Mo, Nb, Cu and Ni can be cited.
Unfortunately, the above-described method for determination or judgment poses a problem of the inconsistent accuracy of the determination or judgment, and also a skilled inspector is needed because the determination or the judgment result depends on the skill of inspector.
A steel material inspection apparatus for making the above-described determination stably and accurately has been proposed (for example, refer to JP3482265B). Unfortunately, the steel material inspection apparatus described in JP3482265B cannot be used to make the above-described judgment stably and accurately. Therefore, it is still desired to develop an apparatus and method capable of making the above-described judgment stably and accurately.